Hmmm. The two cartesian principles ? As in his dualism? mind and matter ? Seems to me to be re-stating the hard problem. Asking what is the relationship between the two seems to me to be the same as asking how one could arise from the other. (edit: Well I guess it's more specifically how they interract, but that's also part of the hard problem, it's just that asking how they interract pre supposes dualism, and we'e skipped some steps. There are some really compelling arguments out there for illusionism too.) David chalmers himself (who outlines and formalizes the hard problem) entertains some kind of double aspect monism, as does Bertrand Russell before him, and some branches of Hindu philosophy.
Look, I like Schopenhauer, he's a good writer and has interesting intuitions on all sorts of stuff (not so much on females
), but I never really understood his concept of will. Seems he doesn't really define it. He just introspects, sees his own intentionality and extrapolates it as the thing that makes up the fabric of the world. I mean it's interesting, but for me intention is a FUNCTIONAL aspect of the mind, and is not the defining aspect of phenomenality. I can easily conceive of a cognition that has no will of it's own but has a subjective experience. Say a machine that has a single qualia of red for example. That's all it does. Perceives red and has an accompanying subjective sensation of it. Where's the "will" ? I mean "will" seems to be synonymous with desire, the ability for a cognition to pose a goal and exert force towards achieving it. I don't see how this is a universal aspect of anything. This is why the "hard problem" as a contemporary formalization of the problem is for me, the most superior formulation so far, it isolates what we are talking about very specifically and why throughout the ages we have had this fucking weird dualistic intuition, after all why the hell would it cross anyone's mind to talk about souls? What's the referent ? How odd. It turns out we're not talking about will, or perception, or desire, or emotions, or any of the basic or highly complex functions of the mind, we're talking about the subjective sensation that accompanies all these functions. It's incredibly clarifying. You can't answer a question unless it's been posed properly, that's why it's revolutionary.
Double aspect monism is a reasonable answer to this crazy problem for all sorts of reasons, it's certainly a competing theory. Chalmers himself seems to be a double aspect monist in some sense, same for Bertrand Russell.
PS: I am a very naughty mod who derails threads, I am now going out but on return I will possibly split this discussion from this thread.